N-cyanoethylated ortho and meta toluenediamine compositions and process for making them

ABSTRACT

The invention provides N-cyanoethylated toluenediamines (CNTDAs), processes for synthesizing them, and compositions containing them. In preferred embodiments, the CNTDAs are represented by the following formula:  
                 
 
     where the nitrogen atoms are ortho or meta to each other on the aromatic ring. The CNTDAs are particularly suitable for use as latent curing agents for epoxy resins.

BACKGROUND OF THE INVENTION

[0001] This invention relates to aromatic amines, more particularly toN-cyanoethylated ortho-toluenediamine and N-cyanoethylatedmeta-toluenediamine, a process for making them, and their use as epoxycuring agents.

[0002] It is known to use amines, such as aliphatic or aromatic amines,for the curing of epoxy resins. See, e.g., “Handbook of Epoxy Resins” byH. Lee and K. Neville, McGraw Hill Book Co., 1967. The aromatic aminescurrently available provide high Tg, good fracture toughness andexcellent chemical resistance for adhesive and composite applications,but suffer from several shortfalls. Aromatic amines typically used asepoxy curatives, such as methylenedianiline (MDA) anddiethyltoluenediamine (DETDA), are usually considered to be highlytoxic. In addition, the potlife of such aromatic amines is of aninsufficient duration to consider the amines to be latent curatives. MDAand DETDA, for example, have very long potlives of up to 12 to 24 hours,but do not provide a potlife of several days, which is desired in alatent curing agent. Moreover, such aromatic amines cannot be used withsolid epoxy resins for powder coating applications.

[0003] The epoxy industry has employed many types of curative blends inan attempt to maximize the desired application properties, but in mostcases at the expense of other properties. Additives such asaccelerators, tougheners, reactive diluents and non-reactive diluentsare employed to maximize a desired property but again to thedeterioration of other properties. A number of good references areavailable on this subject including: Lee and Neville's, “Handbook ofEpoxy Resins,” cited above, and W. R. Ashcroft, “Curing Agents for EpoxyResins,” in B. Ellis (ed.). “Chemistry and Technology of Epoxy Resins,”Blackie Academic and Professional, London (1993), pp. 37-73.

[0004] Others in the epoxy industry have developed novel amines inattempting to optimize curative properties. For example, Japanese Patent2963739 (1999) describes the use ofsubstituted-N-phenyl-1,3-propanediamines as liquid epoxy curatives whichdo not B-stage during cure and thus yield a fully cured epoxy resin. Thesubstituted-N-phenyl-1,3-propanediamines described therein arerepresented by the following chemical formula:

[0005] where R is hydrogen, lower alkyl group, lower alkoxyl group orhalogen. Although the method of synthesis of these curatives is notdisclosed, other references teach methods for synthesizing aromaticamines.

[0006] For example, European Patent 0 067 593 (1982) describes thecyanoethylation of para, meta, and ortho phenylenediamine to generate3,3′-(p,m or o-phenylenedi-imino)-dipropanenitrile:

[0007] EP 0 067 593 teaches the use of water as the solvent andconcentrated hydrochloric acid as the catalyst to obtain thedicyanoethylated product.

[0008] Elderfield et al., 68 J. Amer. Chem. Soc. 1262 (1949), describesthe synthesis of β-p-anisidinopropionitrile by boiling p-anisidine andacrylonitrile in acetic acid.

[0009] Cookson et al., “The Cyanoethylation of Amines and Arsines,” J.Chem. Soc. 1949, pp. 67-72, describes the cyanoethylation of aniline byheating to 150° C. a mixture of aniline and acrylonitrile in thepresence of excess acetic acid in an autoclave to generate2-cyanoethylaniline and bis-2-cyanoethylaniline. The reference furtherdescribes the reaction of diphenylamine and acrylonitrile in an excessof acetic acid using a catalytic amount of fine copper powder togenerate diphenyl-2-cyanoethylamine.

[0010] Braunholtz et al., “The Preparation of Bis(2-cyanoethyl)Derivatives of Aromatic Primary Amines, and Their Conversion into1:6-Diketojulolidines,” J. Chem. Soc., 1952, pp. 3046-3051, describesthe cyanoethylation of aniline, m-toluidine, p-toluidine, p-anisidineand p-chloroaniline in an excess of acetic acid.

[0011] Braunholtz et al., “The Preparation of Bis(2-cyanoethyl)Derivatives of Aromatic Primary Amines, and Their Conversion into1:6-Diketojulolidines. Part II,” J. Chem. Soc., 1953, pp. 1817-1824,describes the cyanoethylation of several different aromatic primarymonoamines in an excess of acetic acid using various metal catalysts toselectively generate mono and di-cyanoethylated derivatives.

[0012] All references cited herein are incorporated herein by referencein their entireties.

BRIEF SUMMARY OF THE INVENTION

[0013] The invention provides cyanoethylated toluenediamines, processesfor synthesizing them, compositions containing them and methods forusing them to cure epoxy resins. In preferred embodiments, thecyanoethylated toluenediamines are represented by the following formula:

[0014] where the nitrogen atoms are ortho or meta to each other on thearomatic ring.

[0015] With regard to the present invention and throughout thespecification and claims the terms “cyanoethyl toluenediamine(s)”,“cyanoethylated toluenediamine(s)”, “N-(cyanoethyl) toluenediamine(s)”and “N-(cyanoethylated) toluenediamine(s)” are used interchangeably.

DETAILED DESCRIPTION OF THE INVENTION

[0016] The most preferred cyanoethylated toluenediamines of theinvention are suitable for use as epoxy resin curing agents.Cyanoethylated toluenediamines where the nitrogen atoms are ortho ormeta to each other on the aromatic ring have been found to beparticularly suitable for this purpose. Thus, the most preferredcyanoethylated toluenediamines of the invention are cyanoethylatedproducts of ortho-toluenediamine represented by the following FormulasI-IV:

[0017] Formulas I-IV above are the cyanoethylated products ofortho-toluenediamine (OTD). Formulas I-II are based on2,3-toluenediamine (TDA) and Formulas III-IV are based on 3,4-TDA. Acommercial isomer mix of OTD is typically 60/40 2,3-TDA/3,4-TDA. Usingcommercial grade OTD therefore leads to cyanoethylated isomer mixtures.

[0018] Formulas V-VII above are the cyanoethylated products ofmeta-toluenediamine (MTD). Formula V is based on 2,6-TDA and Formulas VIand VII are based on 2,4-TDA.

[0019] Cyanoethylated products of OTD are prepared by reacting OTD withacrylonitrile (ACN) at elevated temperature in the presence of an acidand a protic solvent (e.g., water) for a period of time adequate forreaching the desired extent of conversion to the cyanoethylated product.Cyanoethylated products of MTD are prepared by reacting MTD with ACN atelevated temperature in the presence of an acid and a protic solvent(e.g., water) for a period of time adequate for reaching the desiredextent of conversion to the cyanoethylated product. The followingequation illustrates a preferred cyanoethylation reaction of theinvention.

[0020] In the preparation of cyanoethylated OTD, either the purecompounds 2,3-TDA or 3,4-TDA, or isomer mixtures, such as 60/402,3-TDA/3,4-TDA, can be reacted with ACN. In fact, any blend or mixtureof the TDA isomers may be used. The preferred reactant mixture comprisescommercial grade OTD.

[0021] In the preparation of cyanoethylated MTD, either the purecompounds 2,4-TDA, 2,6-TDA, or isomer mixtures such as 80/202,4-TDA/2,6-TDA can be reacted with ACN. Any blend or mixture of the TDAisomers can be used. The preferred reactant mixture comprises commercialgrade MTD.

[0022] The molar ratio of reactants, moles of OTD and/or MTD to moles ofACN, can vary from about 10:1 to about 1:10. The molar ratio used willaffect the rate of reaction and the product distribution, but as thefinal product is purified, the final product quality is unaffected. Tomaximize yield and efficiency, the desired molar ratio is from 0.95:1.0to about 1.0:2.0 with the optimum being about 1.0:1.2.

[0023] The cyanoethylation reaction is conducted using at least one acidcatalyst. The acid catalyst can be any mineral, carboxylic, super orsupported acid, including but not limited to hydrochloric acid, sulfuricacid, phosphoric acid, acetic acid, propionic acid, para-toluenesulfonicacid, triflic acid (trifluoromethanesulfonic acid) and Nafion® superacid catalyst from DuPont, which is a bead-form strongly acidic resin,i.e., a copolymer of tetrafluoroethylene andperfluoro-3,6-dioxa-4-methyl-7-octenesulfonyl fluoride, converted to theproton (H+) form. The preferred acid catalysts are hydrochloric acid andNafion catalyst with Nafion catalyst being most preferred.

[0024] Any protic solvent can be used in the cyanoethylation, includingbut not limited to water, methanol, ethanol, isopropanol, n-propanol,etc.

[0025] The cyanoethylation reaction can be conducted over a temperaturerange from about 50° C. to about 150° C. within a pressure range of fromabout atmospheric pressure up to about 900 psi (6.21 MPa). The reactiontime is dependent on the reaction temperature, pressure and the desiredextent of the reaction as measured by gas chromatography (GC). Thereaction of TDA with ACN can generate not only a mono-cyanoethylatedproduct (CNTDA) but also a di-cyanoethylated product (DCNTDA). Thus, atany given time during the cyanoethylation there is, for example, amixture of unreacted TDA, CNTDA and DCNTDA, as described according tothe following Equation V:

[0026] The cyanoethylated product mixture can be hydrogenated to provideaminopropylated TDAs, which are also useful as epoxy curing agents. Suchaminopropylated TDAs and a process for making them, are disclosed in theinventors' copending U.S. patent application, having the Attorney DocketNo. 061 79USA, entitled “AMINOPROPYL-TOLUENEDIAMINES AND THEIR USE ASEPOXY CURING AGENTS”, and filed on even date with the presentapplication.

Purification

[0027] The crude product resulting from cyanoethylation is a slurrymixture of starting TDA, the desired mono-cyanoethylated TDA (in thecase of OTD, cyanoethylated OTD or CNOTD, and in the case of MTD,cyanoethylated MTD or CNMTD), di-cyanoethylated TDA byproduct (DCNOTDand/or DCNMTD), water and catalyst. The composition of the organicportion of the crude slurry product will vary depending on the reactionconditions, catalyst type and reaction time. Typical composition rangesfor OTD-based reactions are 20/70/10 to 5/75/20 weight %OTD/CNOTD/DCNOTD. Typical composition ranges for MTD-based reactions are20/70/10 to 5/75/20 weight % OTD/CNMTD/DCNMTD. Although the crudeproduct is satisfactory as a curative for epoxy resins, it is moredesirable to use the purified CNOTD and/or CNMTD. This purification maybe accomplished by any method known to one skilled in the art, but thepreferable method is simply washing the crude cyanoethylated TDA with asolvent, such as methanol, ethanol, propanol or isopropanol, again amethod well known to the art. Very high purity cyanoethylated TDA can beobtained by recrystallization of the crude cyanoethylated TDA in anappropriate solvent, such as those listed above for washing the crudecyanoethylated TDA (although the washing and recrystallization solventsneed not be identical). Depending on the washing or recrystallizationconditions, the purified product can have an assay ranging from about 90to 99.9% with the chief impurities being TDA and di-cyanoethylated TDAbyproduct, with a small amount of acid catalyst. Again, none of theseimpurities will impair the performance attributes imparted by thiscurative to a cured epoxy resin formulation.

Use of Cyanoethylated Aromatic Amines as Epoxy Curatives

[0028] The crude, purified and high purity grades of cyanoethylatedtoluenediamine are mixed thoroughly with an epoxy resin and heated toeffect curing. The stoichiometry employed preferably ranges from 0.5 N—Hequivalent of the CNTDA per equivalent of epoxide moieties in the epoxyresin to 1.5 N—H equivalent of the CNTDA per equivalent of epoxide. Morepreferably, the stoichiometry ranges from 0.9 to 1.1 N—H equivalent perepoxide with a 1.0:1.0 ratio being most preferred.

[0029] Any epoxy resin can be employed, including but not limited to thediglycidyl ether of bisphenol A and/or bisphenol F. Solvents such as analcohol, phenol, aliphatic or aromatic hydrocarbon, esters, ethers andthe like can be used. Reactive diluents such as aromatic and aliphaticglycidyl ethers and esters can also be used as well as various types offillers and colorants.

[0030] The cyanoethylated aromatic amines of the invention are excellentcuratives for epoxy resins, providing both latency and the performanceproperties of an aromatic amine curative, particularly chemicalresistance and Tg. In addition, the amines of the invention are solidsat room temperature.

[0031] The invention will be illustrated in more detail with referenceto the following Examples, but it should be understood that the presentinvention is not deemed to be limited thereto.

EXAMPLE 1 Cyanoethylation of 3,4-Toluenediamine Using Nafion Catalyst

[0032] A 3000 ml 4-necked round bottom flask was equipped with amechanical stirrer, thermometer, condenser, nitrogen purge and droppingfunnel. The vessel was charged with 500 parts of 3,4-toluenediamine, 436parts of deionized water and 3.0 parts of Nafion catalyst. The mixturewas heated to 80-86° C. and 322 parts of ACN were added drop-wise over athirty-minute period. The mixture was refluxed for 11 hours, cooled toroom temperature and collected. The organic phase of the reactionmixture contained 3.2% acrylonitrile, 5.4% 3,4-toluenediamine, 80.1%mono-cyanoethylated 3,4-toluenediamine (CN-3,4-OTD) and 11.2%di-cyanoethylated 3,4-toluenediamine (DCN-3,4-OTD), according to gaschromatographic (GC) analysis. The crude CN-3,4-OTD reaction mixture wasfiltered to collect the CN-3,4-OTD product, washed with ethanol anddried in air. An 80% yield of CNOTD (573 g) was obtained, which had amelting point of 124.8° C. The CNOTD as analyzed by GC contained 0.2%OTD, 99.1% CNOTD and 0.7% DCNOTD.

Use of Purified CN-3,4-OTD as Epoxy Curative

[0033] The purified CN-3,4-OTD was mixed with Epon 828 epoxy resin andevaluated for heat of reaction and Tg by Differential ScanningCalorimetry (DSC). Thus, 33.0 g of CN-3,4-OTD were added to 100.0 g ofEpon 828 and mixed thoroughly for 2 minutes using high shear agitation.The DSC data obtained immediately after mixing were: Onset Temperatureof 99° C., Maximum Heat of 145° C., ΔH of 325 j/g and Tg of 1 14° C.

[0034] The purified CN-3,4-OTD was mixed with DER 642 solid powderedepoxy resin and evaluated for heat of reaction and Tg by DSC. Thus, 2.92g of CN-3,4-OTD were added to 26.5 g of DER 642U and mixed thoroughlyfor 30 minutes using a ball mill. The DSC data obtained immediatelyafter mixing were: Onset Temperature of 96° C.; Maximum Heat of 145° C.;ΔH of 190 j/g and Tg of 146° C.

EXAMPLE 2 Cyanoethylation of 60/40 2,3-/3,4-OTD Using Hydrochloric Acidas Catalyst

[0035] A 2000 ml 4-necked round bottom flask was equipped with amechanical stirrer, thermometer, condenser, nitrogen purge and droppingfunnel. The vessel was charged with 523 parts of OTD, 502 parts ofdeionized water and 0.3 parts of concentrated hydrochloric acid. Themixture was heated to 80-86° C. and 477 parts of ACN were addeddrop-wise over a 30-minute period. The mixture was refluxed for 28hours, cooled to room temperature and collected. The organic phase ofthe reaction mixture contained 15.4% ACN, 10.4% OTD, 59.8%mono-cyanoethylated 2,3-/3,4-toluenediamine (CNOTD) and 13.6%di-cyanoethylated 2,3-/3,4-toluenediamine (DCNOTD), according to GCanalysis.

EXAMPLE 3 Cyanoethylation of 60/40 2,3-/3,4-OTD Using Nafion Catalyst

[0036] A 2000 ml 4-necked round bottom flask was equipped with amechanical stirrer, thermometer, condenser, nitrogen purge and droppingfunnel. The vessel was charged with 523.5 parts of OTD, 505 parts ofdeionized water and 1.0 parts of Nafion catalyst. The mixture was heatedto 80-86° C. and 477 parts of ACN were added drop-wise over a 30-minuteperiod. The mixture was refluxed for 23 hours, cooled to roomtemperature and collected. The organic phase of the reaction mixturecontained 8.8% ACN, 19.5% OTD, 61.1% CNOTD and 9.8% DCNOTD according toGC analysis. The crude CNOTD reaction mixture was filtered to collectthe CNOTD product, washed with ethanol and dried in air. A 54% yield ofCNOTD (405 g) was obtained, which had a melting point of 111.7° C. TheCNOTD as analyzed by GC contained 0.35% OTD, 99.65% CNOTD and 0.0%DCNOTD.

Use of Purified CNOTD as Epoxy Curative

[0037] The purified CNOTD was mixed with Epon 828 epoxy resin andevaluated for heat of reaction and Tg by DSC. Thus, 33.0 g of CNOTD wereadded to 100.0 g of Epon 828 and mixed thoroughly for 2 minutes usinghigh shear agitation. The DSC data obtained immediately after mixingwere: Onset Temperature of 85.4° C., Maximum Heat of 147° C., ΔH of 302j/g and Tg of 144° C.

EXAMPLE 4 Cyanoethylation of 3,4-toluenediamine Using 1-Propanol asSolvent

[0038] A 500 ml 4-necked round bottom flask was equipped with a magneticstir bar and stirrer, thermometer, condenser, nitrogen purge anddropping funnel. The vessel was charged with 104.8 parts of3,4-toluenediamine, 100 parts of 1-propanol and 0.3 parts of Nafioncatalyst. The mixture was heated to 80-86° C. and 95 parts ofacrylonitrile were added drop-wise over a 30-minute period. The mixturewas refluxed for 46 hours, cooled to room temperature and collected. Theorganic phase of the reaction mixture contained 10.3% acrylonitrile,25.6% 3,4-toluenediamine, 50.9% mono-cyanoethylated 3,4-toluenediamineand 7.2% di-cyanoethylated 3,4-toluenediamine according to GC analysis.

EXAMPLE 5 Cyanoethylation of 2,4-toluenediamine Using Nafion Catalyst

[0039] A 5000 ml 4-necked round bottom flask was equipped with amechanical stirrer, thermometer, condenser, nitrogen purge and droppingfunnel. The vessel was charged with 54.7 parts (0.45 mole) of2,4-toluenediamine, 49.0 parts of deionized water and 0.3 parts ofNafion catalyst. The mixture was heated to 76° C. and 47.3 parts (0.9mole) of ACN were added drop-wise over a 30-minute period. The mixturewas refluxed for 16 hours, cooled to room temperature and collected. Theorganic phase of the reaction mixture contained 10.7% acrylonitrile,1.7% 2,4-toluenediamine, 71.3% mono-cyanoethylated 2,4-toluenediamine(CN-2,4-MTD) and 14.9% di-cyanoethylated 2,4-toluenediamine(DCN-2,4-MTD), according to GC analysis. The crude CN-2,4-MTD reactionmixture was phase separated to remove the aqueous layer and dried underreduced pressure at 125° C. A 96% yield of CN-2,4-MTD (76 g) wasobtained which was a dark viscous liquid. The crude CN-2,4-MTD had anamine value of 312.2 meg KOH/g.

Use of Crude CN-2,4-MTD as Epoxy Curative

[0040] The crude CN-2,4-MTD was mixed with Epon 828 epoxy resin andevaluated for heat of reaction and Tg by DSC. Thus, 3.3 g of CN-2,4-MTDwere added to 10.0 g of Epon 828 and mixed thoroughly for 2 minutesusing high shear agitation. The DSC data obtained immediately aftermixing were: Onset Temperature of 140° C., Maximum Heat of 187° C., ΔHof 374 j/g and Tg of 116° C.

EXAMPLE 6 Cyanoethylation of 80/20 2,4-/2,6-Toluenediamine Using NafionCatalyst

[0041] A 500 ml 4-necked round bottom flask was equipped with amechanical stirrer, thermometer, condenser, nitrogen purge and droppingfunnel. The vessel was charged with 55.15 parts (0.45 mole) of 80/202,4-/2,6-toluenediamine, 54.6 parts of deionized water and 0.26 parts ofNafion catalyst. The mixture was heated to 86° C. and 47.7 parts (0.9mole) of ACN were added drop-wise over a 30-minute period. The mixturewas refluxed for 24 hours, cooled to room temperature, phase separated,dried at 125° C. under reduced pressure and collected. The crudecyanoethylated 2,4-/2,6-toluenediamine reaction mixture was a darkviscous liquid containing 3.2% 2,4-/2,6-toluenediamine, 70.8%mono-cyanoethylated 2,4-/2,6-toluenediamine and 24.4% dicyanoethylated2,4-/2,6-toluenediamine according to GC analysis.

Use of Crude CN-2,4-/2,6-toluenediamine as Epoxy Curative

[0042] The crude cyanoethylated 2,4-/2,6-toluenediamine was mixed withEpon 828 epoxy resin and evaluated for heat of reaction and Tg by DSC.Thus, 3.3 g of cyanoethylated 2,4-/2,6-toluenediamine were added to 10.0g of Epon 828 and mixed thoroughly for 2 minutes using high shearagitation. The DSC data obtained immediately after mixing were: OnsetTemperature of 148° C., Maximum Heat of 194° C., ΔH of 372 j/g and Tg of127° C.

EXAMPLE 7 Cyanoethylation of 80/20 2,4-/2,6-Toluenediamine Using NafionCatalyst

[0043] A 3000 ml 4-necked round bottom flask was equipped with amechanical stirrer, thermometer, condenser, nitrogen purge and droppingfunnel. The vessel was charged with 1033 parts (8.5 mole) of 80/202,4-/2,6-toluenediamine, 1047 parts of deionized water and 1.0 parts ofNafion catalyst. The mixture was heated to 80-86° C. and 669 parts (12.6mole) of ACN were added drop-wise over a 30-minute period. The mixturewas refluxed for 23 hours, cooled to room temperature, phase separatedand collected. The crude cyanoethylated reaction mixture contained 2.1%2,4-/2,6-toluenediamine, 71.9% cyanoethylated 2,4-/2,6-toluenediamineand 5.6% di-cyanoethylated 2,4-/2,6-toluenediamine according to GCanalysis.

Purification of Cyanoethylated 2,4-/2,6-toluenediamine

[0044] The crude cyanoethylated 2,4-/2,6-toluenediamine was washed twicewith 500 mL of water, dissolved in 1 liter of 1-propanol and filtered toremove Nafion catalyst. The filtrate was transferred to a 3-liter roundbottom flask equipped with a magnetic stirrer, thermocouple, nitrogenbubbler, 18-inch packed column with condenser, vacuum connecter andcollection flask. The vessel contents were slowly heated to 125° C.,during which time the 1-propanol was distilled off. Once at 125° C., thepressure of the system was slowly reduced to 10 mm Hg. A heart cut wastaken over a distillation temperature range of 180-190° C. at 10 mm Hg.The heart cut obtained was found to contain 0.4%2,4-/2,6-toluenediamine, 98.2% monocyanoethylated2,4-/2,6-toluenediamine and 1.4% dicyanoethylated2,4-/2,6-toluenediamine. The semisolid purified cyanoethylated2,4-/2,6-toluenediamine had a melting range of 33-60° C. The purifiedcyanoethylated 2,4-/2,6-toluenediamine was then recrystallized 2 timesfrom isopropanol to obtain a purple crystalline solid with a meltingpoint of 63° C. and a GC analysis of 0.0% 2,4-/2,6-toluenediamine, 98.9%cyanoethylated 2,4-/2,6-toluenediamine and 1.1% dicyanoethylated2,4-/2,6-toluenediamine.

Use of Purified CN-2,4-/2,6-toluenediamine as Epoxy Curative

[0045] The purified cyanoethylated 2,4-/2,6-toluenediamine was mixedwith Epon 828 epoxy resin and evaluated for heat of reaction and Tg byDSC. Thus, 3.3 g of cyanoethylated 2,4-/2,6-toluenediamine were added to10.0 g of Epon 828 and mixed thoroughly for 2 minutes using high shearagitation. The DSC data obtained immediately after mixing were: OnsetTemperature of 146° C., Maximum Heat of 186° C., ΔH of 379 j/g and Tg of112° C.

[0046] While the invention has been described in detail and withreference to specific examples thereof, it will be apparent to oneskilled in the art that various changes and modifications can be madetherein without departing from the spirit and scope thereof.

We claim:
 1. An N-cyanoethylated toluenediamine.
 2. The N-cyanoethylatedtoluenediamine of claim 1, represented by the following formula:

where the nitrogen atoms are ortho or meta to each other on the aromaticring.
 3. The N-cyanoethylated toluenediamine of claim 1, having thedesignation N-(2-amino-6-methylphenyl)-3-aminopropionitrile.
 4. TheN-cyanoethylated toluenediamine of claim 1, having the designationN-(2-amino-3-methylphenyl)-3-aminopropionitrile.
 5. The N-cyanoethylatedtoluenediamine of claim 1, having the designationN-(2-amino-5-methylphenyl)-3-aminopropionitrile.
 6. The N-cyanoethylatedtoluenediamine of claim 1, having the designationN-(2-amino-4-methylphenyl)-3-aminopropionitrile.
 7. The N-cyanoethylatedtoluenediamine of claim 1, having the designationN-(5-amino-6-methylphenyl)-3-aminopropionitrile.
 8. The N-cyanoethylatedtoluenediamine of claim 1, having the designationN-(3-amino-6-methylphenyl)-3-aminopropionitrile.
 9. The N-cyanoethylatedtoluenediamine of claim 1, having the designationN-(3-amino-4-methylphenyl)-3-aminopropionitrile.
 10. A process forpreparing the N-cyanoethylated toluenediamine of claim 1, said processcomprising contacting a toluenediamine with acrylonitrile to providesaid N-cyanoethylated toluenediamine.
 11. The process of claim 10,conducted in a protic solvent containing an acid catalyst.
 12. Theprocess of claim 11, wherein said protic solvent is at least one memberselected from the group consisting of water, methanol, ethanol,isopropanol and n-propanol.
 13. The process of claim 11, wherein saidacid catalyst is at least one member selected from the group consistingof hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid,propionic acid, para-toluenesulfonic acid, triflic acid and Nafioncatalyst.
 14. The process of claim 11, wherein said acid catalyst ishydrochloric acid or Nafion catalyst.
 15. The process of claim 11,wherein a molar ratio of toluenediamine to acrylonitrile is from0.95:1.0 to about 1.0:2.0.
 16. The process of claim 11, conducted withina temperature range from about 50° C. to about 150° C. and within apressure range from about atmospheric pressure up to about 900 psi (6.21MPa).
 17. In a method of curing an epoxy resin with a curing compositioncontaining an amine, the improvement wherein the amine is theN-cyanoethylated toluenediamine of claim
 1. 18. The method of claim 17,wherein said N-cyanoethylated toluenediamine is represented by thefollowing formula:

where the nitrogen atoms are ortho or meta to each other on the aromaticring.
 19. The method of claim 17, wherein said N-cyanoethylatedtoluenediamine is N-(2-amino-6-methylphenyl)-3-aminopropionitrile. 20.The method of claim 17, wherein said N-cyanoethylated toluenediamine isN-(2-amino-3-methylphenyl)-3-aminopropionitrile.
 21. The method of claim17, wherein said N-cyanoethylated toluenediamine isN-(2-amino-5-methylphenyl)-3-aminopropionitrile.
 22. The method of claim17, wherein said N-cyanoethylated toluenediamine isN-(2-amino-4-methylphenyl)-3-aminopropionitrile.
 23. The method of claim17, wherein said N-cyanoethylated toluenediamine isN-(5-amino-6-methylphenyl)-3-aminopropionitrile.
 24. The method of claim17, wherein said N-cyanoethylated toluenediamine isN-(3-amino-6-methylphenyl)-3-aminopropionitrile
 25. The method of claim17, wherein said N-cyanoethylated toluenediamine isN-(3-amino-4-methylphenyl)-3-aminopropionitrile.